An old nation’s exotic city (3,7)
I believe the answer is:
san antonio
'city' is the definition.
(San Antonio is an example)
'an old nation's exotic' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'exotic' is an anagram indicator.
'an'+'o'+'nations'='anonations'
'anonations' is an anagram of 'SAN ANTONIO'.
(Other definitions for san antonio that I've seen before include "Texan city, home to the Alamo" , "city in the New World" , "Texan mission location" .)